This invention relates to a filtering apparatus suitably employed in filtering cutting oils containing metal chips therein (which oil will be referred to as "waste oil" hereinafter).
A variety of waste oil filtering apparatus are known which are adapted to filter waste oils containing both coarse and fine metal chips (hereinafter referred to as "chips") which are generated during cutting of metal workpieces. In one prior art filtering apparatus, a filtering drum (hereinafter referred to as "drum") includes a fine mesh filtering cloth stretched thereabout which is capable of filtering out fine chips as well as coarse chips. The drum is adapted to hold waste oil thrown therein and is rotatably mounted within a cutting oil collection tank whereby as the drum is rotated, the waste oil is centrifuged to separate the chips and cutting oil. The separated chips are carried out of the drum by means of a conveyor mechanism whereas the cutting oil from which the chips have been separated is forced to pass through the filtering cloth and is collected in the cutting oil collection tank and finally taken out of the collection tank. However, since the fine mesh filtering cloth stretched about the periphery of the drum is also required to filter out heavy coarse chips of the waste oil in addition to fine chips, the filtering cloth is easily subjected to severe damage. Thus, in the art to which the present invention portions, any mechanism which avoids damage to the filtering cloth has been desired up to the present time.